Phosphinothioates



3,077,431 PHOSPHHNUTHEOATE?) Joseph W. Baker, Kirkwood, Peter E.Newallis, Crestwood, and John P. Chupp, Kirhwood, Mo., assignors toMonsanto Chemical Company, St. Louis, Mo., a corporation of Delaware NoDrawing. Filed Jan. 14, 195i), Ser. No. 2,337 Claims. (Cl. 167-92) Thisinvention relates to new anduseful phosphinothioates and to methods ofmaking same. Additionally this invention relates to insecticidalcompositions containing the new phosphinothioates as an activeingredient.

The new compounds of this invention can be termed l-propen-2'ylphosphinothioates and can be represented by the structure wherein R andR have the above described significance and wherein X is a halogenhaving an atomic number above 9 but not above 35 (i.e. chlorine orbromine, but

preferably chlorine) with a substantially equimolecular amount of anester of the structure wherein A has the above described, significance,in the presence of an inert organic liquid or solvent (eg. acetone,methyl ethyl ketone, benzene, toluene, xylene, carbon tetrachloride,ethyl acetate, isopropyl acetate, etc.) and a hydrogen halide scavengingagent (e.g. sodium carbonate, potassium carbonate, the tertiary organicamines such as triethyiarnine, tributylamine, dimethylaniline, pyridine,lutidine, l-methyl piperidine, etc.) in an amount atleast sullcient toabsorb the hydrogen halide by-product. The scavenging agent can be addedin toto at the beginning of the r L'b-tion or throughout the course ofthe reaction. While a wide range of reaction temperatures can beemployed provided the system is fluid (i.e. the temperature ismaintained above the freezing point of the system and up to andincluding the boiling point of the system) it is pre ferred to employ areaction temperature in the range of from about 20 C. to about 120 C.

As illustrative of the preparation of the new compounds of thisinvention is the following:

Example I To a suitable reaction vessel equipped with a thermometer,agitator and reflux condenser is charged approximately 17.4 parts byweight (substantially 0.15 mol) of methyl acetoacetate, approximately30.4 parts by weight (substantially 0.30 rnol) of trietiylarnine,approximately 19.2 parts by weight (substantially 0.15 rnol) ofdimethylphosphinothioic chloride, and approximately 150 parts by weightof benzene. The mixture is then heated at reflux for 4 hours. Thereaction mass is then cooled Patent "thee 3,0714% Patented Feb. l2, 1%63to room temperature and washed with four 150 parts by weight portions ofwater. The so-washed reaction mass is then subjected to vacuumdistillation C. at 10 mm.) to remove the benzene. The residue, an ambercolored liquid, is O-(1-methoxycarbonyl-1-propen-2-yl)dimethylphosphinothioate (86.6% yield) which is soluble in acetone andbenzene but insoluble in water.

Employing the above procedure but replacing dirnethylphosphinothioicchloride with an equimolecular amount of diethylphosphinothioic chloridethere is obtained O-( 1- methoxycarbonyl-l-propen-Z-yl)diethylphosphinothioate which material is insoluble in water but solublein acetone.

Employing the procedure of Example I but replacing methyl acetoacetatewith an equimolecular amount of methyl acetothioacetate there isobtained O-(l-(methylthio)carbonyl l-propen-Z-yl)dimethylphosphinothioate which material is insoluble in water butsoluble in acetone.

In the process of this invention any inert organic liquid or mixture ofinert organic liquids can be used provided at least one of the reactantsis soluble therein. The methods by which the phosphinothioates: of thisinvention are isolated will vary slightly with the reactants employedand the product produced. Further purification by selective. solventextraction or by absorptive agents such as activated carbon or clays canprecede the removal of the inert organic liquid or solvent. Additionallyan inert organic solvent can be added to and in the purification byabsorptive agents. However, the product is generally satisfactory forinsecticidal purposes without further purification.

It will be understood that the terms insect and insecticide are usedherein in their broad common usage to include spiders, mites, ticks, andlike ests which are not in the strict biological sense classed asinsects. Thus the usage herein conforms to the definitions provided byCongress in Public Law 104, the Federal Insecticide, Fungicide, andRodenticide Act of 1947, Section 2, subsection h, wherein the terminsect is used to refer not only to those small invertebrate animalsbelonging mostly the class Insecta, comprising six-legged, usuallywinged forms, as beetles, bugs, bees, flies, and so forth, but also toother allied classes as arthropods whose members are Wingless andusually have more than six legs, such as spiders, mites, ticks,centipedes, and wood lice.

Of the new compounds those found to be particularly useful forinsecticidal purposes are those of the structure wherein R and R arelike or unlike alkyl radicals containing not more than two carbon atoms(i.e. methyl or ethyl) and wherein A is sulfur or oxygen. Asillustrative of the preferred phosphinothioates of this invention arethe following:

O-(1-methoxycarbonyl-1-propen-2-yl) dimethylphosphinothioate O-(l-methoxycarbonyl-l-propen-Z-yl) diethylphosphinothioate O-( 1-(methylthio carbonyll -propen-2-yl) dimethylphosphinothioate O-( 1-(methylthio) carbonyl-l-propen-Z-yl) diethylphosphinothioate O-(l-methoxycarbonyl-l-propen-Z-yl) methylethylphosphinothioate Thesecompounds can be prepared conveniently by reacting in an anhydroussystem at a temperature in the range of 20 C. to C. the appropriatephosphinothioic chloride with a substantially equimolecular amount oreither methyl acetoacetate or methyl acetothioacetate in the presence ofan inert organic liquid or solvent and a hydrogen chloride scavengingagent in an amount at least sufiicient to absorb the by-product hydrogenchloride.

As further illustrative of the phosphinothioates of this invention arethe following:

diisobutyl- The phosphinothioates of this invention are effectiveagainst a wide variety of insect pests. As illustrative of the activitybut not limitative thereof is the following:

One gram of O-(l-methoxycarbonyl-l-propen-2-yl) dimethylphosphinothioateWas dissolved in sufiicient acetone to make a concentrated solutionthereof. Approximately 0.1 cc. of sorbitan monolaurate polyoxyethylenederivative (a commercial water-soluble non-ionic emulsifying agent) isthen mixed with the concentrate. To this mixture and with agitation isadded suihcient water to provide an aqueous emulsion having aconcentration of 0.025% by weight of O-(l-rnethoxycarbonyl-l-propen-Z-yl) dimethylphosphinothioate. Thereupon lima bean plant leavespreviously infested with the two-spotted spider mite, Tetranychustelarius (L.), are dipped in the aqueous emulsion, withdrawn, and setaside for observation. At the end of 48 hours a 100% kill of the mobilestages of the mite was noted. Seven days after setting the test specimenaside residual activity was confirmed, a 90% kill of both the restingstage and the ova stage being noted. Similar results against the mobile,resting and ova stages of the same mite are obtained employingO-(l-methoxycarbonyl-l-propen-2-yl) diethylphosphino thioate.

Employing O-(l-methoxycarbonyl-1-propene-2-yl) dimethylphosphinothioateat a concentration of ppm. against yellow fever mosquito larvae, Aedesaegypti, 100% kill was observed.

Contact activity was also observed against plum curculio, Conotrachelusnenupltar, employing the compounds of this invention.

Systemic activity was also observed against a wide variety of insects.For example against the two-spotted spider mite, Tetrancychus telarius(L.), a 100% kill was observed employingO-(l-methoxycarbonyl-l-propen-Z- yl) dimethylphosphinothioate at aconcentration of 0.01% by weight.

Although the phosphinothioates of this invention are useful per se incontrolling a wide variety of insect pests, it is preferable that theybe supplied to the pests or to the environment of the pest or pests in adispersed form in a suitable extending agent.

In the instant specification and appended claims it is to be understoodthat the term dispersed is used in its widest possible sense. When it issaid that the phosphinothioates of this invention are dispersed, itmeans that the particles of the phosphinothioates of this invention maybe molecular in size and held in true solution in a suitable organicsolvent. It means further, that the particles may be colloidal in sizeand distributed throughout a liquid phase in the form of suspensions ofemulsions or in the form of particles held in suspension by wettingagents. It also includes particles which are distributed in a semi-solidviscous carrier such as petrolatum or soap or other ointment base inwhich they may be actually dissolved in the semi-solid or held insuspension in the semisolid with the aid of suitable wetting oremulsifying agents. The term dispersed also means that the particles maybe mixed with and distributed throughout a solid carrier providing amixture in particulate form, e.g.,

ellets, granules, powders, or dusts. The term dispersed also includesmixtures which are suitable for use as aerosols including solutions,suspensions, or emulsions of the phosphinothioates of this invention ina carrier such as dichloroditluoromethane and like fiuorochloroalkaneswhich boil below room temperature at atmospheric pressure.

In the instant specification and appended claims it is to be understoodthat the expression extending agent includes any and all of thosesubstances in which the phosphinothioates of this invention aredispersed. it in cludes, therefore, the solvents of a true solution, theliquid phase of suspensions, emulsions or aerosols, the semi-solidcarrier of ointm-ents and the solid phase of particulate solids, e.g.pellets, granules, dusts and powders.

The exact concentration of the phosphinothioates of this inventionemployed in combatting or controlling insect pests can vary considerablyprovided the required dosage (i.e. toxic or lethal amount) thereof issupplied to the pests or to the environment of the pests. When theextending agent is a liquid or mixture of liquids (eg. as in solutions,suspensions, emulsions or aerosols) the concentration of thephosphinothioate employed to supply the desired dosage generally will bein the range of 0.001 to 50 percent by weight. When the extending agentis a semi-solid or solid, the concentration of the phosphinothioateemployed to supply the desired dosage generally will be in the range of0.1 to 25 percent by weight. From a practical point of view, themanufacturer must supply the agriculturist with a low-cost concentrateor spray base or particulate solid base in such form that, by merelymixing with Water or solid extender (e.g. powdered clay or talc) orother low-cost material available to the agriculturist at the point ofuse, he will have an easily prepared insecticidal spray or particulatesolid. In such a concentrate composition, the phosphinothioate generallywill be present in a concentration of 5 to 95' percent by weight, theresidue being any one or more of the wellknown insecticidal adjuvants,such as the various surface active agents (e.g., detergents, a soap orother emulsifying or Wetting agent, surface-active clays), solvents,diluents, carrier media, adhesives, spreading agents, humectants, andthe like.

There are a large number of organic liquids which can be used for thepreparation of solutions, suspensions, or emulsions of thephosphinothioates of this invention. For example, isopropyl ether,acetone, methyl ethyl ketone, dioxane, cyclohexanone, carbontetrachloride, ethylene dichloride, tetrachloroethane, hexane, heptaneand like higher liquid alkanes, hydrogenated naphthalenes, solventnaphtha, benzene, toluene, xylene, petroleum fractions (eg. thoseboiling almost entirely under 400 F. at atmospheric pressure and havinga flash point above about F., particularly kerosene), mineral oilshaving an unsulfonatable residue above about 80 percent and preferablyabove about percent. In those instances wherein there may be concernabout the phytoxicity of the organic liquid extending agent a portion ofsame can be replaced by such low molecular weight aliphatic hydrocarbonsas dipe ntene, diisobutylene, propylene trimer, and the like or suitablepolar organic liquids such as the aliphatic ethers and the aliphaticketones containing not more than about 10 carbon atoms as exemplified byacetone, methyl ethyl ketone, diisobutyl ketone, dioxane, isopropylether, and the like. In certain instances, it is advantageous to employa mixture of organic liquids as the extending agent.

When the phosphinothioates of this invention are to be supplied to theinsect pests or to the environment of the pests as aerosols, it isconvenient to dissolve them in a suitable solvent and disperse theresulting solution in dichlorodifluoromethane or like chlorofluoroalkanewhich boils below room temperature at atmospheric pressure.

The phosphinothioates of this invention are preferably supplied to theinsect pests or to the environment of the insect pests in the form ofemulsions or suspensions. Emulsions or suspensions are prepared bydispersing the phosphinothioates of this invention either per se or inthe form of an organic solution thereof in water With the aid of awater-soluble surfactant. The term surfactant as employed here and inthe appended claims is used as in volume II of Schwartz, Perry andBertchs Surface Active Agents and Detergents (1958, IntersciencePublishers, Inc, New York), in place of the expression emulsifying agentto connote generically the various emulsifying agents, dispersingagents, wetting agents and spreading agents, that are adapted to beadmixed with the active ingredients in the water vehicle or carrier inwhich they are insoluble through lowering the surface tension of thewater (see also Frear Chemistry of Insecticides, Fungicides andHerbicides, second edition, page 280). These surfactants include thewell-known capillar -active substances which may be anion-active (oranionic), cationactive (or cationic), or non-ionizing (or non-ionic)which are described in detail in volumes I and II of Schwartz, Perry andBerchs Surface Active Agents and Detergents 195 8, IntersciencePublishers, Inc., New York), and also in the November 1947 issue ofChemical Industries (pages 811-842), in an article entitled SyntheticDetergents by John W. McCutcheon and also in the July, August, Septemberand October 1952 issues of Soap and Sanitary Chemicals under the titleSynthetic Detergents. The disclosures of these articles with respect tosurfactants, i.e. the anion-active, cation-active and non-ionizingcapillary active substance, are incorporated in this'specification byreference in order to avoid unnecessary enlargement of thisspecification. The preferred surfactants are the Water-soluble anionicsurface active agents and the water soluble non-ionic surface-activeagents set forth in US. 2,846,398 (issued August 5, 1958). In general itis preferred that a mixture of water-soluble. anionic and watersolublenon-ionic surfactants be employed.

The phosphinothioates of this invention can be dispersed by suitablemethods (e.g., tumbling or grinding) in solid extending agents either oforganic or inorganic nature and supplied to the insect pest environmentin particulate form. Such solid materials include, for example,tricalcium phosphate, calcium carbonate, kaolin. hole, kieselguhr, talc.bentonite, fullers earth, pyrophillite, diatomsceous earth, calcinedmagnesia, volcanic ash, sulfur and the like inorganic solid materials,and include, for example, such materials of organic nature as powderedcork, powdered wood, and powdered walnut shells. The preferred solidcarriers are the adsorbent clays. eg. bentonite.

These mixtures can be used for insecticidal purposes in I the dry form,or, by addition of water-soluble surfactants or wetting agents the dryparticulate solids can be rendered wettable by water so as to obtainstable aqueous dispersions or suspensions suitable for use as sprayablecompositions.

For special purposes the phosphinothioates of this invention can bedispersed in a semi-solid extending agent such as petrolatum or soap(e.g., sodium stearate or oleate or palmitate or mixtures thereof) withor without the aid of solubility promotors and/ or surfactants ordispersing agents.

In all of the forms described above the dispersions can be providedready for use in combatting insect pests or they can be provided in aconcentrated form suitable for mixing with or dispersing in otherextending agents. As illustrative of a particularly useful concentrateis an intimate mixture of phosphinothioates of this invention with aWater-soluble surfactant which lowers the surface tension of Water inthe weight proportions of 0.1 to 15 parts of surfactant with sufficientof the phosphinothioate of this invention to make 100 parts by Weight.Such a concentrate is particularly adapted to be made into a spray forcombatting various forms of insect pests (particularly mites) by theaddition of Water thereto. As illustrative of such a concentrate is anintimate mixture of 95 parts by weight of O-(1-rnethoxycarbonyl-1-propene-Z-yl) dimethylphosphinothioate and 5 partsby weight of a Water-soluble non-ionic surfactant such as thepolyoxyethylene derivative of sorbitan monolaurate.

Another useful concentrate adapted to be made into a spray forcombatting insect pests (particularly mites) is a solution (preferablyas concentrated as possible) of a phosphinothioate of this invention inan organic solvent therefor. The said liquid concentrate preferablycontains dissolved therein a minor amount (e.g., 0.5 to 10 percent byweight of the weight of the new insecticidal agent) of a surfactant (oremulsifying agent), which surfactant is also water-soluble. Asillustrative of such a concentrate is a solution ofO-(l-methoxycarbonyl-lpropen-Z-yl) diethylphosphinothioate in benzenewhich solution contains dissolved therein a Water-soluble alkylarylsulfonate anionic surfactant.

Of the surfactants aforementioned in preparing the various emulsifiable,wettable or dispersible compositions or concentrates of this invention,the anionic and non-ionic surfactants are preferred. Of the anionicsurfactants, the particularly preferred are the well known Water-solublealkylaryl sulfonatcs, e.g. sodium decylbenzene sulfonate and sodiumdodecylbenzene sulfonate. Of the non-ionic surfactants, the particularlypreferred are the water-soluble polyoxyethylene derivatives ofalkylphenols (particularly isooctylphenol) and the water solublepolyoxyethylene derivatives of theniono-higher fatty acid esters ofsorbitan.

In all of the various dispersions described hereinbefore forinsecticidal purposes, the active ingredient can be one or more of thecompounds of this invention. The compounds of this invention can also beadvantageously employed in combination with other pesticides, including,for example, nematocides, bactericides, fungicides, and herbicides. inthis manner it is possible to obtain mixtures which are effectiveagainst a wide variety of pests and other forms of noxious life.

In controlling or cornbatting insect pests the phosphinothioates of thisinvention either per se or compositions comprising same are supplied tothe insect pests or to their environment in a lethal or toxic amount.This can be done by dispersing the new insecticidal agent orinsecticidal composition comprising same: in, on or over an infestedenvironment or in or over an environment the insect pests frequent, e.g.agricultural soil or other growth media or other media infested with theinsect pests or attractable to the pests for habitational or sustenanceor propagational purposes, in any conventional fashion which permitscontact between the insect pests and the phosphinothioates of thisinvention. Such dispersing can be brought about by applying the newphosphinothioates per se or sprays or particulate solid compositionscontaining same to a surface infested with the insect pests orattractable to the pests, as for example, the surface of an agriculturalsoil or other media such as the above ground surface of plants by any ofthe conventional methods, e.g. power dusters, boom and hand sprayers,and spray dusters. Also for sub-surface application such dispersing canbe carried out by simply mixing the new insecticidal spray per se orinsecticidal agent or particulate solid compositions comprising samewith the infested environment or with the environment the insect pestsfrequent, or by employing a liquid carrier for the new insecticidalagent to accomplish sub-surface penetration and impregnation thereoftherein.

While this invention has been described with respect to certainembodiments, it is to be understood that it is not so limited and thatvariations and modifications thereof obvious to those skilled in the artcan be made without departing from the spirit or scope thereof.

What is claimed is:

l. A phosphinothioate of the structure to 4 carbon atoms and wherein Ais selected from the group consisting of oxygen and sulfur.

2. A phosphinothioate ot the structure R s U i -C=oH-fiaom R OH; 0wherein R and R are alkyl radicals containing not more than two carbonatoms and wherein A is selected from the group consisting of sulfur andoxygen. 3. A phosphinothioate of the structure \il /P-O-C=CHCOCI-Is RCH3 0 wherein R and R are alkyl radicals containing not more than twocarbon atoms.

4. O-(l-methoxycarbonyl-l-propen-2yi) dimethylpnosphinothioate.

5. O-(l-methoxcarbonyl-l-wopen-Z-yl) diethylphosphinoihioate.

6. O-[l-(methylthio)carbonyl-1-propen-2-yl1 dim-ethylphosphinothioate.

7. The method of making phosphinothioates of the structure \H/1OO=CH-(ACH3 R 011 0 wherein R and R are alkyl radicals containing 1 to4 carbon atoms and wherein A is selected from the group consisting ofsulfur and oxygen which comprises reacting in an anhydrous system anacid halide of the structure R S /PX RI wherein R and R have theaforedescribed significance and wherein X means a halogen having anatomic number higher than 9 but not higher than 35 with an ester of thestructure wherein A has the aforedescribed significance in the presenceof a hydrogen halide scavenging agent.

8. The method of making O-(l-methoxycarbonyl-L propen-Z-yl)dimethylphosphinothioate which comprises reacting in an anhydrous systemmethyl acetoacetate and dimethylphosphinothioic chloride in the presenceof triethylamine.

9. An insecticidal composition comprising a compound of claim 1dispersed in an extending agent.

10. An insecticidal composition comprising a compound of claim 1dispersed in a semi-solid extending agent, the composition containing0.1 to 25 percent by weight of said compound of claim 1.

11. An insecticidal composition comprising a compound of claim 1dispersed in a solid extending agent, the composition containing 0.1 to25 percent by weight of said compound of claim 1.

.12. An insecticidal composition comprising a compound of claim '1dispersed in a liquid extending agent, the composition containing 0.G0lto percent by weight of said compound of claim 1.

l3. An insecticidal concentrate comprising a com pound of claim 1dispersed in an organic solvent therefor and having dissolved therein aminor amount of a surfactant, said concentrate forming an emulsion withWater upon agitation therewith.

14. An insecticidal composition comprising a compound of claim 2dispersed in an adsorbent clay, the composition containing 0.1 to 25percent by weight of said compound of claim 2.

15. An insecticidal concentrate comprising a compound of claim 2 and aninsecticidal adjuvant, said concentrate containing from S to percent byweight of the compound of claim 2.

16. An insecticidal concentrated adapted to be made into a spraya-blecomposition by the addition of Water comprising a compound of claim 2 inadmixture with a Water-soluble surfactant in the weight proportion of0.1 to 15 parts of surfactant and sufiicient of said compound 01' claim2 to make parts by Weight.

17. The method of controlling insects which comprise contacting theinsects with a toxic amount of a compound of claim 1.

18. The method of controlling insects which comprises contacting theinsects with a toxic amount of a compound of claim 2.

19. The method for protection of plants against insect attack whichcomprises applying to the plant an insecticidal amount of at least onecompound of claim 2.

20. The method of controlling insects which comprises contacting theinsects with a toxic amount of the compound of claim 4.

Gilbert Nov. 3, 1959

1. A PHOSPHINOTHIOATE OF THE STRUCTURE